Broken Penske Clevis.

[TomInPA]

Another try at the high-res image..

 

[Fred W]

Yes, the intent of the large diameter threaded stud coming out of the Clovis yoke is to allow some ride height adjustment. Having had your adjustment bottomed out should have put the least possible stress on the part.

One thing that appears in al, of the broken part pictures is an alarming amount of "grain" in the broken casting. I'll defer to one of the mechanical engineers but I wouldn't have expected to see so much striation of the metal crystals.

 

[ionbeam]

Given that they break, people then ride with them for thousands of miles broken like that with no problems it looks like it just needs to be make with one flange

It appears that the part could use a stress relieving process.

 

[Ignacio]

Given that they break, people then ride with them for thousands of miles broken like that with no problems it looks like it just needs to be make with one flange

About the time I took off my second one and got the cold shiver...I actually thought about that. Am I just a lucky fool or are two flange sides just fancy-schmancy overkill.

I decided to have another cold shiver....I think two is better and have this spiffy Ohlins now anyway.

 

[TomInPA]

The problem is, it can fail on either side at any time. It seems when one side fractures, it must relieve stress on the other side, but it's just a matter of time before someone has a total failure and drops the bike onto the rear tire. Glad to have a new part, but I will periodically inspect it now. I just think the lightweight alloy is unnecessary.

 

[RaYzerman19]

Re-did and made some more measurements if this helps:

RaceTech clevis wall thickness - 0.23"

Shoulder on Gen3A shock bolt - 0.21" (0.02" difference) (also noted it is not a separate spacer as depicted in the parts diagram)

Width of RT clevis opening - 0.184"

Length of suspension pivot spacer - 0.181" (not much to worry about, call it a slide fit as you have to wiggle to get the spacer in between)

Gen3A (steel) clevis wall thickness - 0.195" (steel clevis will squeeze in to 0.18" spacer, nothing to worry about).

See photo - RT solution - long bolt with long (16mm) spacer to act as shoulder). Note, for reference corroded band on the left end was in the clevis hole on my Gen2.

Similar measurements on new Penske clevis wall thickness and opening, and Gen1/2 shock bolt shoulder would tell you if there's any clamping forces involved. By my calcs above, using stock Gen3 bolt in the RT would potentially pull in the clevis walls 0.02" approx. Bad or acceptable makes for a good theory, but ideally that should be zero to give the Penske the best chance at survival.

 

[Mr Bill]

Given that they break, people then ride with them for thousands of miles broken like that with no problems it looks like it just needs to be make with one flange

It appears that the part could use a stress relieving process.

Maybe my shock was worn, but my rear tire was slipping and leaving the ground pretty often just before I pulled it and found it was broken. Handling went to hell after bike was airborne in VT on bridge construction whoop dee do and then landing really hard on the next whoop.

I just looked at my three year old replacement clevis and it still looks like new. Remember mine broke with the wrong hardware bolt installed so maybe I don't have to keep checking it now for cracks

 

[majicmaker]

Given that they break, people then ride with them for thousands of miles broken like that with no problems it looks like it just needs to be make with one flange It appears that the part could use a stress relieving process.

One flange will now have All the shear and tension on it probably making it crack faster and then not have the second flange as a failsafe. Not a good idea. :no:

 

[hppants]

I'm glad to read that Penske is making this right. Equally glad to know that this hasn't hurt anyone.

But I'm MOSTLY glad that my bud got his bike fixed in time for SFO.

Ray - thanks for the measurements. Like you, I was hoping for a delta of much closer to zero between the spacer width and the Clevis gap. I wonder what a washer to close the gap would do?

 

[majicmaker]

Yes, the intent of the large diameter threaded stud coming out of the Clovis yoke is to allow some ride height adjustment. Having had your adjustment bottomed out should have put the least possible stress on the part.
One thing that appears in al, of the broken part pictures is an alarming amount of "grain" in the broken casting. I'll defer to one of the mechanical engineers but I wouldn't have expected to see so much striation of the metal crystals.

Fred, that's normal for a failure like that one. It's relatively thick. Metal having a grain structure will not snap like a piece of glass. It's more like tearing apart like a piece of wood.

 

[RaYzerman19]

Ray - thanks for the measurements. Like you, I was hoping for a delta of much closer to zero between the spacer width and the Clevis gap. I wonder what a washer to close the gap would do?

I suggested that earlier on, however, I re-thought that and I'm not so sure the washer idea is still a good one. Better to use the RaceTech bolt/spacer idea (spacer is 16 mm OD, 12 mm ID and 16mm long) doesn't have to be as long for sure, but anything longer than the OEM bolt's shoulder would be good. Otherwise, the thing to do is measure up the Penske clevis and Gen1/2 bolt shoulder, determine what's needed from there.

 

[Fred W]

Rayzerman's measurements need to be performed on the Penske clevis and stock shoulder bolt.

If the clevis is as thick as Ray's Race Tech clevis is, then the stock bolt head is hitting the clevis when tightened, and that would explain all of the broken clevises.

Yes, a fix could be made by installing a shim on the stock shoulder bolt with an ID the diameter of the bolt, and the OD the diameter of the shoulder. The alternative would be to find a bolt with a longer shoulder, though I'm not sure it needs to be as long as the Race Tech one.

 

[hppants]

Fred - thanks. I re-read Ray's post and now realize that he was not measuring the delta with the Penske. I am curious to know what it is now.

If it were my bike, and the delta was more than 0.050", then I'd put a shim in it. I'm not convinced it would fix the problem (because I'm too ignorant to know), but I don't think it can hurt.

 

[RaYzerman19]

My reasoning for the washer idea and hesitation is this....... any washer on the right side (in my picture) pushes the pivot spacer left, so how much washer? Only enough to make the total suspension pivot spacer + washer a line to line fit into the clevis (need to measure the Penske setup to make a determination). More than that and on could run out of room at the grease seal on the right end, and I don't think one wants to push the spacer into the clevis on the left end. You want total bearing area in that big hole, and no gap/split between the pivot spacer and bolt shoulder (since the shoulder on mine has a slight radius, not sure if shoulder to spacer would be a seamless tight unit. If it is, then OK).

I think it better as a permanent fix to have a spacer on the left end (16mm OD, 12mm ID) that is a tad longer than the thickness of the clevis leg.. e.g. 1/4"+ to prevent the bolt head from clamping the assembly, use a standard bolt with appropriate thread length........ The RaceTech bolt/spacer is/are unnecessarily long, so essentially I'm just saying use a shorter version of that....... let actual measurements be your guide.

Meanwhile, in a pinch, with the stock hardware, I would just snug it up until the sandwich is firm and not torque it since the nut has locking features (you could add loctite as well), it shouldn't come loose in the short term if you had to go for a ride. Not my preferred long term fix though, just me.

 

[eflyguy]

I just realized - my FJR has a Penske.. I should climb under there with a feeler gauge!

Now.. where did I put it?

 

[Fred W]

My reasoning for the washer idea and hesitation is this....... any washer on the right side (in my picture) pushes the pivot spacer left, so how much washer?

No, I would not add any shim (that's what it would be technically, not a washer) on the right side of your photo. I would put it on the left side, between the shoulder of the bolt and the inner bearing race.

It's OD would have to be equal to or smaller than the OD of the inner race and bolt shoulder. The bearing race would still be in the original, correct position as it butts into the clevis yoke on the small hole side, and the bolt's head would be spaced further away from hitting the yoke and putting any pressure on it, which there should be none of.

 

[eflyguy]

Well, I find this interesting..

Gaps on each side clevis and linkage above the bolt were 0.012" and 0.014"

There was ZERO gap below.

So I pulled out the calipers - clevis is 44.87mm (sorry) at the shoulder, and 44.35mm below the bolt.

 

[eflyguy]

Well.. I'm an idiot.. my shock (8975) does not have the same clevis - no ride height adjustment.

That said, I'm still concerned about the fact that the clevis appears to be pinched.

 

[eflyguy]

That said - I removed the nut and the clevis opened up 1.4mm !!!!

 

[eflyguy]

Note - I'm not too concerned about mine breaking as there are no sharp corners/small radii anywhere. I still think it wouldn't hurt to put some spacers in, however, to give the linkage a little space to pivot!